Conventional industrial air humidifiers for large buildings and paint booths often employ corrugated cardboard or glass fibers, joined by resins, as absorptive pads for storing water to be evaporated into a stream of air. These absorptive pads often are arranged in rectangular panels many feet high and several feet thick. Overhead pipes carry water which cascades down over and is absorbed by the absorptive pads. An air stream is then forced through the absorptive pads with the air stream picking up moisture to increase the humidity of the air stream.
Industrial humidifiers which utilize the above described absorptive pads have a number of problems. First, to ensure the absorptive pads are sufficiently saturated, a great deal of water must be supplied to the absorptive pads. Consequently, a large amount of water also drains from the absorptive pads into collection trays located beneath the absorptive pads. The waste water is often treated for recirculation. This additional waste water burdens a facility's waste water treatment equipment and adds to the cost of operating the facility.
Second, in order for the absorptive pads to hold sufficient quantities of water to achieve the necessary humidification, the absorptive pads are often several feet thick. A large pressure head is needed to force the air stream through the absorptive pad. This, in turn, requires a larger fan or blower motor to develop a sufficient pressure head. Also, the large size of the absorptive pad increases the overall size of the humidifier.
Third, when the humidifier is shut down, the flow of water to the absorptive pad typically is stopped. This leads to the absorptive pad eventually drying out. A significant amount of time is necessary to then resaturate the absorptive pad during start up from a dried initial state.
Fourth, because of the massive size of the absorptive pad and the large amount of water stored therein, it is difficult to quickly and precisely adjust the humidity of the air stream exiting the humidifier to a desired level. This lack of precision can be particularly detrimental in paint booths where tight tolerances on humidity levels are critical to the proper adherence of paint to parts. Accordingly, there is a need for an industrial humidifier which can quickly and precisely adjust the humidity of an air stream.
Finally, the absorptive pads accumulate scale from the cascading water. When the pads become sufficiently encumbered with scale, the pads have to be replaced. Otherwise, particles of scale may break loose and contaminate the humidified air stream.
The present invention seeks to overcome the above-identified problems associated with conventional industrial humidifiers for buildings and paint booths which utilize large absorptive pads.